1. Field of the Invention
The present invention relates to the design and testing of safety critical electronic devices, and in particular to a method of testing a safety critical target electronic device implemented in a particular type of configurable integrated circuit device, such as a field programmable gate array (FPGA) or a complex programmable logic devices (CPLD), that employs on target hardware description language based fault injection.
2. Description of the Related Art
For safety critical electronic devices, such as, without limitation, circuits/systems used in the control and/or detection of trains in railroad or mass transit systems, it is typically necessary to perform an extensive safety analysis of the device before it can be implemented in the field. The purpose of the safety analysis is to establish that, if particular random faults, e.g., shorts or other similar component failures, in the device were to occur (which in fact may happen from time to time), the risk of a resulting hazard would be acceptable because such faults would: (i) be detected by software diagnostics forming a part of the device, and (ii) result in the device behaving in a safe fashion (i.e., defaulting to a safe operational state).
In addition, many current safety critical electronic devices, such as those from the railroad or mass transit industry described above, are implemented using configurable integrated circuit devices, such as field programmable gate arrays or complex programmable logic devices, that are able to be selectively configured by a user after manufacture using a hardware description language such as VHDL. However, the effects of faults in such configurable integrated circuit devices cannot be quantified with an acceptable confidence level using current known qualitative techniques, such as failure mode and effects analysis (FMEA) and failure mode, effects and criticality analysis (FMECA). As a result, there are currently no known techniques for effectively performing an extensive quantitative fault based safety analysis of a safety critical electronic device that is implemented using a configurable integrated circuit device such as an FPGA or CPLD. A need for such a technique thus exists. Furthermore, given the current trend toward increased use of configurable integrated circuit devices in modern electronics design, the need for such a technique is particularly keen.